El display device and method for manufacturing same

Abstract

An EL display device of the present invention includes a plurality of pixel electrodes, wiring, a common electrode, a plurality of light-emitting layer portions, and a protective layer. The pixel electrodes are formed in one-to-one correspondence with a plurality of pixels. The wiring is formed in at least one of a plurality of intervals between the pixels. The common electrode is formed above each of the pixel electrodes and is in electrical connection with the wiring. The common electrode is made of alkali metal or alkaline earth metal. The light-emitting layer portions are each located between a corresponding one of the pixel electrodes and the common electrode. The protective layer is located on the common electrode, preventing oxidization thereof. The EL display device suppresses voltage drop in the common electrode, while also suppressing reduction in a property of electron injection to the light-emitting layer portions.

Description

TECHNICAL FIELD[0001]The present invention relates to an electroluminescence (EL) display device in which a light-emitting layer is located between a plurality of pixel electrodes, which are each located in a corresponding one of a plurality of pixels, and a common electrode which is common to all of the pixels. In particular, the present invention relates to an EL display device including wiring for supplying electrical power to the common electrode (referred to below as electrical supply wiring).BACKGROUND ART[0002]In a typical EL display device, a common electrode is located continuously throughout a plurality of pixels located on a substrate. An electrical voltage is applied to a portion of a light-emitting layer in each of the pixels, via the common electrode, from a periphery of the substrate. Consequently, due to electrical resistance of the common electrode, there is a tendency for electrical voltage applied to light-emitting layer portions in a central region of the substra...

AI Technical Summary

Benefits of technology

The present invention relates to an EL display device which uses a common electrode made of alkali metal or alkaline earth metal. This prevents the formation of alkali metal oxide or alkaline earth metal oxide between the common electrode and the wiring, which can cause an increase in contact resistance. Additionally, the use of alkali metal or alkaline earth metal results in improved electron injection into the light-emitting layer portions due to their lower work function compared to oxide conductors. Consequently, the present invention improves the performance and efficiency of the EL display device.

Problems solved by technology

As a consequence, an amount of electrical power supplied to the second electrode 1008 from the electrical supply wiring 1003 is decreased, which makes it difficult to effectively suppress the problem of voltage drop in the second electrode 1008.

Furthermore, the above prevents exciton-polaron quenching, and also prevents temporary reduction in internal quantum efficiency when power is switched on.

A main cause of the decrease in standardized lifetime may be due to reduction in light extraction efficiency.

Next, luminance was caused to deteriorate by driving using a constant electrical current.

Furthermore, as deterioration in switched on luminance increased, difference between decrease in PL intensity for different Ba layer film thicknesses increased.

However, the aforementioned strategy is undesirable from a point of view of production cost.

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